petcock does nothing

I just purchased a '82 XJ650J a couple weeks ago(my first bike). The petcock does nothing....fuel doesnt flow in any position. I get a small trickle between RES and PRI. I took off the front cover and removed the knob to expose the O ring and rubber thing with 4 holes. The hole on the left of the petcock has a ball bearing lodged in it and the bottom hole is empty. Sorry I dont know the tech terms, but hey, im a noob Any help will be appreciated!

 

Welcome to the gang kalinin, I hope we can help you out here. It sounds like your internals are in the right places. Any deposits or grit in the 4 hole ring? It could well be a couple of things. First, make sure that the vaccum diaphragm (small pipe behind the main fuel outlet pipe) is functioning by putting a small piece of tubing on it and sucking down on it. Don't worry, fuel should not be passing through this tube (although it is possible if your diaphragm is ruptured so be very cautious, use clear line). If fuel flows (which it should in ON and RES) then, your problem is the vaccum line from #2 intake manifold. If nothing is flowing, I'll put dollars to doughnuts that your fuel screen has been plugged, necessitating the removal of the petcock and cleaning of the screen. Good luck to you and welcome once again!

 

The petcock was pretty clean on the inside, the o-ring and the 4 hole ring are in good shape. I applied vaccum and fuel flows, but when I reattach everything the bike wont start unless i use a shot of starting fluid. It'll start but only stay running if I apply some throttle. As soon as I let off the throttle, it dies. The petcock screen is clear and there is no inline fuel filter. Im going to add one if I can get this thing to run....

 

As soon as you let-off the throttle it dies ...

NOT petcock! Other problem.

There would be enough fuel in the bowl -- to keep the engine running ... if only momentarily ... after you close the throttle.

Adjust idle screw to set the idle higher.
Set your Pilot screws to 2.75 turns out and see what happens.

 

Reverse flush the Petcock just to see what happens. You don't have to take it out of the tank. IF the gas in the tank isn't too high ... you can tilt the tank so that the fuel is away from the Petcock ...

With the fuel away from the petcock ... attach a small length of fuel line to the Petcock Fuel Outlet. Duct tape the red straw that comes with the spray can of carb cleaner in to the end of the fuel line. Hook-up the can to the straw and blow a bunch of cleaner in there ... good.

Remove flush gear.
Put on the tank ... test.

 

Set the petcock select lever to PRIME for the flush-out ... sorry, an important detail I fail to mention above.

 

Ok Rick....I'll try that tomorrow....Ive already played with the idle screw to no effect.....

 

Finally had a chance to work on the bike. I adjusted the pilot screws 2.75 turns out....almost worked....turned to 3 out and it starts and runs! Idle is high in 1st gear, about 2500-3000rpm, fine in other gears. I adjusted the idle screw and nothing really happened. If I tinker with the adjustment screw on the throttle on the handlebars the idle changes....now what?

 

Also.....seems when I turn the handlebars to the right, rpms increase....I can ride in 1st gear without having to use any throttle...around 4000rpm when bike is fully warmed up in 1st gear and neutral. The idle speed slowly decreases in neutral, down to about 1100rpms after a couple minutes.

 

The handlebar adjustment is NOT an idle adjustment. That adjuster is a throttle cable -- Free Play -- adjustment. Moving that adjuster in and out tightens and slacks the cable for the throttle grip.

Some people like the cable adjusted close ... with no free-play. Others like a little "room" in the throttle grip.

Overtightening the adjuster will pull all the slack out of the cable ... and then, when adjusted too tight ... shortens itself ... to the point where it lifts the throttle linkage ... as the return spring gives ... to allow the cable to be further tightened. Not good!

You NEED about the width of a dime freeplay ... for the cable to be slack enough to allow the return spring to bring the linkage into contact with the Idle Adjustment Rod (between 2 & 3).

Slack the throttle cable at the handlebar adjuster so that the linkage will completely retract on the tension of the return spring.
Leave it slack.
Adjust the Idle Rod to give you 11-hundred rpm's.

Then ... absent a ColorTuner ... "Old School" tweak the Screws to get your idle smoothed-out.

Once you get the mixture "In the Ballpark" ... the idle will settle-down and ... after sufficient tweaking to get the good idle ... allow you bring the idle down to 975 - 1050 ... by adjusting the Idle Rod.

Once you have arrived at the point where the idle is good ... and can be controlled by the Rod ... head upstairs and take-up the slack in the cable ... leaving just enough slack to insure that the return spring brings the linkage closed against where you set the Rod!

 

Thanks for all the info! Where should I have the idle adjust screw turned to for starters? All the way in? All the way out? Somewhere in between?

 

Flashlight.
Eyeball end of Idle Adjust Rod and linkage "contact" surface.
Back-off rod until no longer touching linkage contact point.
Screw-in until rod just touches linkage contact point.
Eyeball the Knurl on the end of Adjust rod.
3/4 turn in should provide 13-hundred > 18-hundred rpm's (depending on mixture set.)

Start bike. Be prepared to make sudden adjustments.
Tweak knurled Idle Adjust knob (IN for higher -- OUT for slower) as needed to attain satisfactory idle. (Shoot for 950 if the mix screws are all tweaked nice.

If not ... start tweaking!

 

Well, I did exactly as you said Rick, and no dice. Wont idle at all. When I let off the throttle, it sputters for 1/2 second and dies. Ive turned the mixture screws so many times Ive lost count. I adjusted the throttle cable and idle adjust screw just as you instructed....

 

If you've lost count on the mixture screws and I'm sure many of us have also, just start all over again. Keep track of where the bike runs best and you will have a reference point to come back to.

You need slack in the throttle cable, not lots but some. All of your idle adjustments should take place on the knurled knob between the carbs ( pic attached ), as you screw in the idle should go up.
I've never counted how many turns, to me it's not relevant, just listen to the engine speed or watch the tach.

 

Already did that. Slackened the throttle cable, the knurled idle adjustment knob backed off till it just makes contact with the throttle contact.....no matter where I turn the knob, in or out, idle doesnt change. Bike seems to run about the same no matter where I am in the mixture adjustment....at least runs ok in neutral, as long as I apply a little throttle...

 

You need an Ohio Carb Clinic ... BAD!

Real Bad!

Even worse than that !!!

 

If it runs okay with a little throttle, then you should be able to get it to idle the same with the idle adjustment knob. The knob is directly connected to the throttle shaft linkage. As you turn it in, it will push the throttle linkage and open up the butterflies and as they open ( same as twisting the grip ) the engine speed increases. So keep turning it in, the idle should increase.

If some how the threaded end of the throttle adjustment knob is stripped, and as you turn it nothing is moving, then you won't get any results. I just can't picture that thing stripped!

 

The screw isnt stripped or anything, I can watch it push the throttle shaft linkage....idle just doesnt change when it pushes against it....I'll mess with it some more tomorrow I guess.....

 

Highly unlikely ... but the linkage contact point might be bent. If the rod is actually pushing against that contact point ... continue turning the Idle Adjustment Rod in until the bike starts to pick-up some rev's ...

It HAS too. The Idle Adjustment Rod is nothing more than a super-fine threaded-end rod that adjusts the speed of the engine by actually causing the throttle butterfly's to be opened ... in a fine-tune adjustment ... as the rod is screwed in.

 

I give up. Today the bike wont start unless I use some starting fluid. It wont idle no matter what I do. I have no clue how many turns I have on the mixture screws, heck with it, I think Im done...

 

Try doing the "Clunk Test" on the four Vacuum Pistons.
You might be a candidate for needing a refinish on the bores.
Give it a shot.

The Old School Method
Carbuerator Tuning for High Peformance
All rights reserved.

Performance checks prior to commencing carburator tune-up's.

Clunk Test:
Un-sprung vacuum pistons "Clunk" down after being manually lifted to end of travel. (++ Caution: Do not damage needle. ++)

!. Each vacuum piston must rapidly fall-down and go "Clunk".

Yes? Tune.
No? Fix before commencing ANY tuning. Performace related issue.

-30-

 

I'll have to use my Haynes to translate that lol Think im in over my head....

 

Hey drop me a line with your contact info, I have what I need here and a shop to perform all the work in, I can fit you in and get those carbs up and runnin for you. Drop me you info and lets get those carbs done.,..

 

The only thing in my records dealing with -- what seems to me, being limited to just the clues in the thread, -- is an AIR PROBLEM.

If you pulled the Air Jets, particularly the two beneath the diaphragm to clean air passages ... those two Air Jets might be replaced in reverse order.

(++ Note: The information on the placement of these two Air Jets is -- INCORRECTLY REVERSED -- in some Volumes of Haynes Manuals. ++)

When this is the case, air flows are dramatically affected by the incorrect placement and will not be detected when trouble-shooting and relying on the information supplied in the Workshop Manual.

Correct placement:
Looking into the Vacuum Chamber -- with the Air Jets to the Right of the piston bore -- the TOP Jet has the LARGEST metering port. The BOTTOM Jet is the SMALLER one.

 

correct me if i'am wrong but could the balance be so far out that the mixture
won't help
seemed that way on mine, once the balance got close the mixture screws had a effect

 

Sure ... that's why we hope a Bench Sync & a Clunk Test resolves the issue.

People have guessed what the Sync Screws do without any idea of what they really are for!

I needed two-hands, once ... to break loose the over-tightened Sync Screws, on a "Mechanically-challenged" individual's bike. Without a clue as to what they did or what they were for ... he just cranked them down as tight as he possibly could.

Why?

"I was hoping to get a little more speed out of it" he says.

 

Turned out that the carbs were FILTHY! The guy who sold me the bike said he just had the carbs cleaned at a shop before I bought it. Yeah right!

A HUGE thanks to kbarmansr for showing how to break down the carbs and cleaning them and syncing them, the bike now runs great! Thanks to Rickomatic as well for getting me some help!

Ken

 

Thanks.

We knew you were knocking on the door. We just had to find someone to get-up and answer the door.

Kbar ... You Rock!

Now you each have a riding buddy. So, go add some miles on those bikes!

 

Glad that i could be of help. I enjoy turning a wrench and really enjoy bringing one back to the living side. I look forward to some good rides, and hopefully here soon, I'll get my butt in gear and get a Carb Clinic planned for the area.